uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

nixos/modules/programs/turbovnc.nix

@@ -0,0 +1,54 @@
+# Global configuration for the SSH client.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.programs.turbovnc;
+in
+{
+  options = {
+
+    programs.turbovnc = {
+
+      ensureHeadlessSoftwareOpenGL = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to set up NixOS such that TurboVNC's built-in software OpenGL
+          implementation works.
+
+          This will enable <option>hardware.opengl.enable</option> so that OpenGL
+          programs can find Mesa's llvmpipe drivers.
+
+          Setting this option to <code>false</code> does not mean that software
+          OpenGL won't work; it may still work depending on your system
+          configuration.
+
+          This option is also intended to generate warnings if you are using some
+          configuration that's incompatible with using headless software OpenGL
+          in TurboVNC.
+        '';
+      };
+
+    };
+
+  };
+
+  config = mkIf cfg.ensureHeadlessSoftwareOpenGL {
+
+    # TurboVNC has builtin support for Mesa llvmpipe's `swrast`
+    # software rendering to implemnt GLX (OpenGL on Xorg).
+    # However, just building TurboVNC with support for that is not enough
+    # (it only takes care of the X server side part of OpenGL);
+    # the indiviudual applications (e.g. `glxgears`) also need to directly load
+    # the OpenGL libs.
+    # Thus, this creates `/run/opengl-driver` populated by Mesa so that the applications
+    # can find the llvmpipe `swrast.so` software rendering DRI lib via `libglvnd`.
+    # This comment exists to explain why `hardware.` is involved,
+    # even though 100% software rendering is used.
+    hardware.opengl.enable = true;
+
+  };
+}